Fix backward compatibility issue introduced by #126

[Edouard-chin]

• Fixes uninitialized constant ActiveRecord::SessionStore::Session #142
• The goal of Use lazy-load hook: #126 was to lazily require the 'session.rb' file as
  otherwise, we'd load Active::Record base too prematurely during
  the boot process.

This change had the negative effect of breakin apps that were
setting configuration on the Session before the hook was
getting triggered, thus ending up with a "uninitialized constant"
error.

This patches move the session_class assignment when loading then
session.rb file as well as autoloading the
AR::SessionStore::Session constant so that application referencing
it too early will still work.

[kaspth]

While this fixes the issue, it also seems complex.

Would it make more sense to extend the existing accessor seen in #142? Like this:

Rails.application.config.session_store :active_record_store, serializer: :json

[kaspth]

Isn't this duplicated in the session class?

[rafaelfranca]

Not sure if we should se the session_class when loading session. Do we need to do that?

[Edouard-chin]

We can't remove the session_class assignment when loading the session.rb file and just have the assignment in the lazy hook. This is because of the edge case I mentioned in the PR description.

TL;DR If the host application reference Session, "session.rb" gets loaded, the active_record hook is dispatched, at this point the Session constant is not yet defined since the AS hook takes precedence, calling Session one more time in the hook will just raise a undefined constant error. Chicken and egg situation really

[rafaelfranca]

Ok, so we should just require 'active_record/session_store/session'in this hook them. If the file was already required it will just returnfalse`.

[Edouard-chin]

I have a gift for finding overcomplicated solutions 🤦‍♂️ . Thanks!

[Edouard-chin]

I agree it seem over complicated but couldn't find a better alternative.

Would it make more sense to extend the existing accessor seen in

I'm not sure if I understand what you mean, the problem will persist as soon as ActiveRecord::SessionStore::Session is referenced

[kaspth]

From #142 (comment):

# config/initializers/session_store.rb
Rails.application.config.session_store(:active_record_store)

ActiveSupport.on_load(:active_record) do
  ActiveRecord::SessionStore::Session.serializer = :json
end

It's only referenced to set the serializer (unless I'm misunderstanding how the first line works).

[Edouard-chin]

Yeah that code is actually the right way to configure the session.

What we need to fix is the case where ActiveRecord::SessionStore::Session is called outside the on_load(:active_record) hook (like the doc advises to do https://github.com/rails/activerecord-session_store#configuration)

[Edouard-chin]

This should be good to go Rafael/Kasper

[sikachu]

Thank you! I'm going to push out 1.1.3